In many devices such as turbo-generators, engines, machinery, industrial equipment and other combustion type sources, considerable acoustic energy travels with exhaust gasses. The high noise level associated with such devices can be objectionable and must often be reduced. As a result, a wide variety of silencers and other sound attenuation reducing devices have been developed.
Some mufflers or silencers use a series of tubes, baffles and chambers of varying shapes and sizes to alter the path of the exhaust gases over a short distance. While such mufflers may be effective in reducing noise levels, they tend to create undesirably high back pressure on the engine, resulting in lower engine power output and lower efficiency. Other mufflers direct the exhaust gases straight through a perforated tube within a larger tube, with sound absorbing material such as glass wool located between the two tubes. These so called sound absorbing material such as glass wool located between the two tubes. These so called "glass-pack" mufflers produce low back pressure, but are not very effective in reducing noise levels.
Attempts have been made to combine tubes, baffles, and chambers with sound absorbing materials to improve efficiency. While these designs somewhat combine the noise reduction characteristics of the baffle-type muffler and the low back pressure of the straight through type muffler, there remains a need for a silencer which achieves high engine efficiency through minimum increase in back pressure and also achieves maximum reduction in noise. Moreover, designs which have been available can have a number of interconnected parts, which add to their cost and complexity.
Thus, there is a continuing need for improved silencers for use with turbo-generators or the like.